1. Field of the Invention
The present invention relates generally to passenger conveyors such as escalators and moving sidewalks and, more particularly, to the steps of the passenger conveyors.
2. Description of the Prior Art
In general, the escalator, which is one type of passenger conveyors, has an endless series of steps each comprising a tread, a pair of side frame members supporting the tread and a riser. On the other hand, the steps of moving sidewalks each comprise, in general, a tread and a pair of side frame members.
As disclosed in Japanese Utility Model Publication No. 40-16984(16984/65), for example, it has been a conventional technique in connecting a tread and side frame members together that through-holes are formed in the tread through the bottoms of grooves between cleats of the tread, similar through-holes are formed in the side frame members and bolts of a small diameter (usually 3 mm) are inserted into aligned through-holes in the tread and side frame members and screwed into nuts placed on the undersurfaces of the side frame members.
As such, the diameter of the bolts used is limited by the width of each of the grooves formed between the cleats on the tread. As a consequence, a large number of bolts (usually 20-30 bolts) are required to provide the necessary mechanical strength, with a result that the manufacture of a passenger conveyor step involves a large number of troublesome drilling and bolting steps.